Accessibility

Effect-TS library usage in TypeScript — Effect.gen generators, Schema.Struct/Schema.Class definitions, Layer/Context.Tag/Service patterns, Effect.pipe pipelines, Data.TaggedError/Data.Class error types, Ref/Queue/PubSub/Deferred concurrency primitives, Match module, Config providers, Scope/Exit/Cause/Runtime patterns, or any code using Effect's typed error channel (E parameter). Trigger when writing, reviewing, debugging, or refactoring TypeScript code that uses Effect — when you see imports from `effect`, `effect/*`, or any `@effect/*` scoped package (schema, platform, sql, opentelemetry, cli, cluster, rpc, vitest). Also trigger when the user asks about Effect patterns, migration from Promises/fp-ts/neverthrow to Effect, or how to structure an Effect application. Do NOT trigger for React's useEffect, Redux side effects, or general English usage of "effect" unless the context clearly involves the Effect-TS library.

Testing for React/Next.js with Jest, React Testing Library, and Playwright. Use when generating tests, writing unit tests, analyzing coverage, scaffolding E2E tests, configuring Jest, or improving test quality.

Proactively apply when creating new features/components/pages or setting up frontend project structure. Triggers on FSD, feature slicing, Feature-Sliced Design, frontend architecture, layer structure, module boundaries, scalable frontend, slice organization, public API, barrel exports, import rules, Steiger. Use when restructuring React/Next.js/Vue/Remix projects, organizing frontend code, fixing import violations, deciding where code belongs (entity vs feature vs widget vs shared), or migrating legacy codebases. Feature-Sliced Design (FSD) architecture for frontend projects.

Optimize web performance: bundle size, images, caching, lazy loading, and overall page speed. Use when site is slow, reducing bundle size, fixing layout shifts, improving Time to Interactive, or optimizing for Lighthouse scores. Triggers on: web performance, bundle size, page speed, slow site, lazy loading. Do NOT use for Core Web Vitals-specific fixes (use core-web-vitals), running Lighthouse audits (use perf-lighthouse), or Astro-specific optimization (use perf-astro).

Tailwind CSS performance optimization including v4 improvements. PROACTIVELY activate for: (1) Tailwind v4 Oxide engine performance, (2) Lightning CSS minification, (3) reducing CSS bundle size, (4) content config tuning to avoid scanning unused files, (5) safelist for dynamic classes (without bloating), (6) production builds with @apply minimization, (7) critical CSS extraction, (8) HTTP caching of generated CSS, (9) avoiding @apply overuse (utility-first preferred), (10) PurgeCSS / content-detection edge cases. Provides: performance tuning checklist, Oxide engine notes, content config patterns, safelist guidance, and critical-CSS workflow.

HarmonyOS ArkTS application development with ArkUI declarative UI framework. Use when building HarmonyOS/OpenHarmony apps, creating ArkUI components, implementing state management with decorators (@State, @Prop, @Link), migrating from TypeScript to ArkTS, or working with HarmonyOS-specific APIs (router, http, preferences). Covers component lifecycle, layout patterns, and ArkTS language constraints.